[Sheepdog] timestamp epoch log

[Liu Yuan]

This patch set timestamps the epoch log, that is supposed to help admins to
get more info about cluster history.

Liu Yuan (3):
      sheep: use update_epoch_log() to write epoch logs
      sheep: timestamp the epoch log
      sheep: rename var ctime to ct

 collie/cluster.c   |   11 +++++---
 include/sheep.h    |    1 +
 sheep/group.c      |    4 +--
 sheep/ops.c        |    9 +++---
 sheep/sheep_priv.h |    1 -
 sheep/store.c      |   74 ++++++++++++++++++++++++++-------------------------

Thanks,
Yuan